Resolved -
All email reports have been completed correctly and successfully and can be accessed via the Reports section fo the analytics. We will continue to monitor to ensure that no faulty analytics reports remain.
Mar 5, 13:30 PST

Identified -
On the morning of March 5, 2018, we were made aware of a bug that led to email reports having incomplete or no data. We quickly tracked down the bug and repaired it, and are now in the process of recalculating all email reports that were affected. We believe the affected reports were created between February 2018 and now.
Mar 5, 13:20 PST